Structural frame member

ABSTRACT

A frame assembly includes a non-combustible rigid filler sheet supported within a surrounding support frame made from lengths of a structural frame member joined together. The structural frame member has an elongate body extruded from a heat meltable material and has longitudinally extending cavities. Intumescent material is located in selected cavities.

The present invention relates to a structural frame member used inparticular but not exclusively in the construction of window frames,door frames and door leaves.

In the United Kingdom, a British Standard exists, BS 476 Part 20 andPart 22, which stipulates the necessary requirements for achieving afire rating and a 30 minute fire rating is a common fire rating requiredfor windows or door assemblies to be used in public buildings.

Structural frame members are known which are extruded from heat meltablematerials, such as plastics, in particular polyvinylchloride or metalssuch as aluminium.

Since these materials melt with heat, they normally exhibit poor firerating characteristics when exposed to fire conditions, say in abuilding. For example a window assembly including a frame constructedfrom members of polyvinylchloride normally may only have a fire ratingof less than 10 minutes.

It is a general aim of the present invention to provide a structuralframe member formed from a heat meltable material and which enables awindow or door assembly to be constructed therefrom and achieve a muchlonger fire rating than heretofore.

Another general aim of the present invention is to provide a method ofenhancing the performance of an otherwise heat meltable material in theform of a structural member so as to achieve a recognizable fire ratingof at least 30 minutes under the conditions of relevant internationalfire test standards.

According to one aspect of the present invention there is provided astructural frame member including an elongate body extruded from a heatmeltable material, the body including longitudinally extending cavitiesand intumescent material located in selected cavities.

According to another aspect of the present invention there is provided aframe assembly comprising a non combustible rigid filler sheet supportedwithin a surrounding support frame, the support frame comprising lengthsof the structural frame member as defined above jointed together.

Preferably the intumescent material is located in primary cavitiespositioned directly inbetween the edge of the filler sheet and thesurrounding supporting structure to which the support frame is secured,the amount of intumescent material within the primary cavities beingsuch that on intumescence, the foamed intumescent material acts toprovide a compressive force on the filler sheet for providing structuralsupport for the filler sheet after softening/melting of the heatmeltable material.

In addition to or as an alternative to locating intumescent materialwithin said primary cavities, intumescent material is located withinsecondary cavities located to one side of the primary cavities, theamount of intumescent material in each of said secondary cavities beingsuch that after intumescing the intumesced material substantially fillseach cavity and thereby provides a heat insulative barrier.

Preferably the intumescent material located in each cavity is in stripform and is preferably encapsulated in an extruded sheath, as anassembly aid, formed from a compatible plastics material, preferablypolyvinylchloride. Alternatively, an intumescent paste or mastic may beinjected into each cavity.

Preferably the intumescent material is a hydrated sodium silicate.Preferably the lengths of the structural frame member are jointedtogether by welding the lengths together. The heat meltable materialsuch as polyvinylchloride is preferably thermally welded, but chemicalwelding is also envisaged.

In the case of a window assembly, the filler sheet may be any suitablepane of glass but is preferably wire reinforced or chemically orphysically modified in order to provide sufficient fire resistancecommensurate with the frame. The filler sheet may comprise single ormultiple panes of glass.

In the case of a door assembly, the filler sheet may comprise one ormore panes of glass and/or may comprise any suitable non-combustiblesheet material suitable for door constructions, eg. gypsum, calciumsilicate or vermiculite based board.

The heat meltable material is chosen so as to be sufficiently rigid toprovide structural support under normal operating conditions, e.g. attemperatures less than 50° C.

According to another aspect of the present invention there is provided amethod of producing a structural frame member including extruding aframe body from a heat meltable material so as to include longitudinallyextending cavities, and subsequently inserting intumescent material intoselected cavities. Preferably the intumescent material is in strip formand is longitudinally inserted into said selected cavities.

Various aspects of the present invention are hereinafter described withreference to the accompanying drawings in which:

FIG. 1 is a schematic side view of a window assembly according to thepresent invention;

FIG. 2 is a sectional view taken along line II—II in FIG. 1;

FIG. 3 is a schematic view similar to FIG. 2 after exposure to fire;

FIG. 4 is a schematic side view of a door and frame assembly accordingto the present invention;

FIG. 5 is a sectional view taken along line V—V in FIG. 4;

FIG. 6 is a part sectional view similar to FIG. 5 after exposure tofire.

Referring initially to FIG. 1, there is shown a window assembly 10including a window pane 11 supported in a support frame 12. The supportframe 12 extends along each side edge of the pane 11 and is secured inan opening formed in a surrounding support structure 16 such as abuilding wall.

The support frame 12 includes four lengths of a structural frame member14 which are jointed to another preferably by mitre joints 17 asillustrated.

As best seen in FIG. 2, the structural frame member 14 comprises a mainelongate body 15 which is extruded from a heat meltable material such asa plastics material, preferably polyvinylchloride.

The body 15 includes a plurality of cavities 19 defined by internalpartition walls. The majority of the cavities 19 are totally enclosed incross-section, but those located at the surface of the body 15 areopen-sided in cross-section.

The body 15 defines a rebate portion 20 for receiving the window pane11. A strip 22 of intumescent material is located between the edge ofthe window pane 11 and the rebate portion 20 to define a seat for thewindow pane 11. In between the rebate portion 20 and the supportstructure 16 are a pair of primary cavities 19 p. One cavity 19 pcontains a strip 27 of intumescent material and the other cavity 19 p isfilled with non-combustible rigid reinforcing member 28. The reinforcingmember 28 may be omitted and if so, the cavity would contain a strip 27of intumescent material. The reinforcing member 28 is preferablyprovided to give rigidity to the body 15.

The window pane 11 is held in the rebate portion 20 by a separateelongate body member 30 which is lockingly engaged into a groove 31formed in the main body 15. Body member 30 is preferably extruded fromthe same material as the body 15.

Seals 32, 33, for example of silicone rubber, are provided to create aseal between the bodies 15, 30 and the window pane 11. In the embodimentillustrated in FIG. 2 the window pane 11 is a double glazed unitincluding two side by side panes of glass 11 a, 11 b which are sealedtogether by sealing element 11 c.

In use, the window frame 12 is mounted in the structure 16 such thatvertical wall 20 a of the rebate portion 20 faces toward the expected 30source of fire, i.e. in a building, it faces toward the interior of thebuilding.

In the event of a fire, the material of the frame bodies 15, 30 facingthe interior of the building initially soften, then melt and then char.

The intumescent material within cavities 19 p and strip 22 are chosen tobegin intumescing when the material of the frame begins to soften. Thisenables the intumescent material in the primary cavities to expand andseal gaps created by the frame body material as it softens/melts. Inaddition the amount of intumescent material in the primary cavities ischosen such that after intumescing it occupies a far greater volume thanthe volume of the primary cavities 19 p. In this way the intumescentmaterial as it intumesces applies a compressive pressure (indicated byarrow P) inwards of the pane 11 and thereby serve to structurallysupport the pane 11 after collapse of the body 15. This is illustratedschematically in FIG. 3.

The intumescent strip 22 preferably includes an upwardly directed flangeportion 23 which overlies the outer marginable portion of the pane 11.The flange is provided in order to help prevent the pane 11 being pushedsideways toward the non-exposed side of the window when the intumescentmaterial located closer to the exposed side begins to intumesce.

The intumescent material is preferably chosen such that its degree ofexpansion or intumesce is greater in a direction perpendicular to theplane of the strip compared to the direction parallel to the plane.Accordingly, the flange portion 23 is preferably formed such that itsdirection of maximum expansion is perpendicular to the plane of the pane11. Preferably, the reinforcing member 28 is a non-combustible metalsuch as steel.

The cavities 19 s located to the side of the primary cavities 19 p mayalso contain strips of intumescent material.

The amount of intumescent material located in cavities 19 s ispreferably chosen such that after intumescing, the intumesced materialcompletely fills the cavity without causing significant distortion ofthe body 15. The main purpose of the intumescent material in thesecondary cavities is to provide an insulation barrier to transmissionof heat. Such an insulation barrier helps to reduce the likelihood ofdistortion of the reinforcing member 28 due to heat.

Preferably, the intumescent material is enclosed in a sheath 40,preferably formed from a heat fusible material such as polyvinylchloridehaving a softening point lower in temperature than the activationtemperature of the intumescent material.

Preferably the intumescent material is a hydrated sodium silicate. Thismaterial is preferred since it intumesces at a temperature between100-150° C. (the softening temperature of polyvinylchloride being in therange of 80-100° C.) and exhibits good rigidity/mechanical strengthcharacteristics when intumesced. It also exhibits good insulativecharacteristics. It will be appreciated that intumescent materialsexhibiting similar characteristics could be used.

Preferably the intumescent strips are located into the cavities of body15 by insertion in the longitudinal direction.

A door and frame assembly 50 according to the present invention is shownin FIGS. 4 to 6.

The assembly 50 includes structural frame members 114, 115 similar tostructural frame members 14 described above.

A first set of frame members 114 are joined together to define a door 52comprising a rectangular support frame 53 housing a filler sheet 54. Asecond set of structural frame members 115 are joined together to definea door frame 56 surrounding the door 52. Door 52 is hingedly connectedto frame 56 in a conventional manner and the frame 56 is fixed to asupport structure 16 in a conventional manner.

The structural frame members 115 include a first primary cavity 119 pand a second primary cavity 219 p. The first cavity 119 p includes areinforcing member 28 and a strip of intumescent material 140 located onthe inner side (ie. nearest to the door opening) of the reinforcingmember 28. A strip of intumescent material 240 is located within cavity219 p.

The structural members 114 preferably include a central primary cavity319 p housing a reinforcing member 28 and a strip of intumescentmaterial 340 located on the outer side (ie. nearest to the outer side ofthe door) of the reinforcing member 28.

The structural members 114 also preferably include a rebate portion 20similar to that of members 14 for receiving the filler sheet 54. A stripof intumescent material 122 is located between the edge of the fillersheet and the rebate portion 20 to define a seat for the filler sheet54. The sheet 54 is held in the rebate portion 20 by a separate elongatebody member 30 and is lockingly engaged in groove 31 of the main body ina similar manner to that described in relation to the window frameabove.

The structural members 114 include secondary cavities on the front andrear sides of the reinforcing member 28 and are preferably filled withintumescent material 540 in order to provide a heat insulation barrierfor heat shielding the reinforcing member 28 in the event of a fire.

As seen in FIG. 6, under fire conditions, the intumescent material 140,340 expands to fill the gap 70 with intumesced material 140′ and 340′between the door 52 and door frame 56.

The intumescent material 240 and 122 also expand to form intumescedmasses 240′ and 122′ and co-operate with the reinforcing members 28within structural members 114, 115 to provide mechanical support for thefiller sheet 54.

In the illustration of FIG. 6, the parts of the structural members 114,115 which are destroyed by melting are indicated in broken lines. Alsointumescent material 540 located on the fire exposed side of thereinforcing member 28 is shown as being expanded to define an intumescedmass 540′ which forms a heat insulation baffler for shielding thereinforcing member 28.

What is claimed is:
 1. A frame assembly comprising a non-combustible rigid filler sheet supported within a surrounding support frame, the support frame comprising a plurality of structural frame members joined together, each structural frame member including an elongate body extruded from a heat meltable material which melts or softens under fire conditions, the body including a plurality of longitudinally extending cavities and intumescent material located in selected cavities, wherein the intumescent material is encapsulated in an extruded sheath, the intumescent material under fire conditions forming a foamed intumesced material which acts to provide structural support for the filler sheet after softening or melting of the heat meltable material.
 2. An assembly according to claim 1 wherein the lengths of the structural frame member are jointed together by welding.
 3. An assembly according to claim 1 adapted for use as a window frame assembly and wherein the filler sheet comprises one or more panes of glass.
 4. An assembly according to claim 1 adapted for use as a door assembly and wherein the filler sheet comprises one or more panes of glass and/or sheets of suitable non-combustible boards.
 5. A structural frame member for use in the construction of a support frame in a surround, the structural frame member including an elongate body extruded from a heat meltable plastics material, the body having an outer side which in use faces the surround and an inner side located opposite to said outer side and a plurality of longitudinally extending cavities located between said inner and outer sides of said body, a non-combustible rigid reinforcing member housed within one of said cavities and intumescent material located between said reinforcing member and said inner and/or outer side.
 6. A method of producing a structural frame member for use in a surround including extruding a frame body, said frame body having an outer side adapted to face the surround and an inner side located opposite to said outer side, from a heat meltable plastics material so as to include longitudinally extending cavities located between said inner and outer sides of the body, and subsequently inserting a non-combustible reinforcing member into one of said cavities and inserting intumescent material so as to be located between said reinforcing member and said inner and/or outer side.
 7. A method according to claim 6 wherein the intumescent material is in strip form and is longitudinally inserted into said cavities.
 8. A frame assembly comprising a non-combustible rigid filler sheet supported within a surrounding support frame, the support frame comprising a plurality of structural frame members joined together, the structural frame member including an elongate body extruded from a heat meltable material which melts or softens under fire conditions, the body including a plurality of longitudinally extending cavities and intumescent material located in selected cavities, the intumescent material under fire conditions forming a foamed intumesced material which acts to provide structural support for the filler sheet after softening or melting of the heat meltable material, wherein the intumescent material is located in primary cavities positioned directly inbetween the edge of the filler sheet and a surrounding supporting structure to which the support frame is secured in use, the amount of intumescent material within the primary cavities being such that, on intumescence, the foamed intumescent material acts to provide a compressive force on the filler sheet for providing structural support for the filler sheet after softening/melting of the heat meltable material, wherein a non-combustible rigid reinforcing member is located in one of said primary cavities.
 9. A frame assembly according to claim 8 wherein the intumescent material is encapsulated in an extruded sheath.
 10. A frame assembly according to claim 8 wherein the intumescent material is in paste or mastic form.
 11. An assembly according to claim 8 wherein the intumescent material is located in primary cavities positioned directly inbetween the edge of the filler sheet and a surrounding supporting structure to which the support frame is secured in use, the amount of intumescent material within the primary cavities being such that on intumescence, the foamed intumescent material acts to provide a compressive force on the filler sheet for providing structural support for the filler sheet after softening/melting of the heat meltable material.
 12. An assembly according to claim 11 wherein intumescent material is located within secondary cavities located to one side of the primary cavities, the amount of intumescent material in each of said secondary cavities being such that after intumescing the intumesced material substantially fills each cavity and thereby provides a heat insulative barrier.
 13. An assembly according to claim 11 wherein the intumescent material is encapsulated in an extruded sheath.
 14. An assembly according to claim 11 wherein the intumescent material is in paste or mastic form.
 15. A frame assembly comprising: a non-combustible rigid filler sheet supported within a surrounding support frame, the support frame comprising a plurality of structural frame members joined together, each structural frame member including an elongate body extruded from a heat meltable material which melts or softens under fire conditions, the body including a plurality of longitudinally extending cavities and intumescent material located in selected cavities, wherein the intumescent material is encapsulated in an extruded sheath, wherein the intumescent material is located in primary cavities positioned directly inbetween the edge of the filler sheet and a surrounding supporting structure to which the support frame is secured in use, the intumescent material under fire conditions forming a foamed intumesced material which acts to provide structural support for the filler sheet after softening or melting of the heat meltable material, the amount of intumescent material within the primary cavities being such that on intumescence, the foamed intumescent material acts to provide a compressive force on the filler sheet for providing structural support for the filler sheet after softening/melting of the heat meltable material. 